import javax.swing.tree.TreeNode;

/*
 * @lc app=leetcode.cn id=100 lang=java
 *
 * [100] 相同的树
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        return compare(p, q);
    }
    public boolean compare(TreeNode p,TreeNode q){
        //递归结束
        if(p==null&&q!=null){
            return false;
        }else if(p!=null&&q==null){
            return false;
        }else if(p==null&&q==null){
            return true;
        }else if(p.val!=q.val){
            return false;
        }
        //递归处理
        boolean outside=compare(p.left, q.left);
        boolean inside=compare(p.right, q.right);
        return outside&&inside;
    }
}

//熟练写法
// class Solution {
//     public boolean isSameTree(TreeNode p, TreeNode q) {
//         if(p==null&&q==null) return true;
//         if(p==null||q==null) return false;
//         return p.val==q.val&&isSameTree(p.left,q.left)&&isSameTree(p.right,q.right);
//     }

// }
// @lc code=end

